1. Field of the Invention
The present invention relates to an electric vacuum cleaner including a nozzle fitted with a rotating brush for promoting the separation of dust from the surface being cleaned.
2. Description of the Prior Art
An electric vacuum cleaner is known which is provided with a rotating brush in a nozzle for sucking dust together with air so that separation of dust from the surface being cleaned is promoted by rubbing the surface by the rotating brush. Japanese Laid-Open Patent Application No. H7-136082 discloses an electric vacuum cleaner which promotes the separation of dust from the surface being cleaned by directing thereto the slip stream from an electric fan for producing a flow of sucked air. The structure of this cleaner is shown in FIGS. 17 to 19 of the drawings accompanying this specification.
FIG. 17 is a sectional side view of the whole cleaner and FIG. 18 is a sectional top plan view of a nozzle. This cleaner is of upright type with the nozzle 71 being arranged at the bottom of a cleaner body 72. A dust bag 74 is fitted downstream from an electric fan 73. The body 72 includes a cover 75, in which the electric fan 73 and the dust bag 74 are housed. The cover 75 includes a lid 76 for putting the dust bag 74 into the body 72 and taking it out of the body. The body 72 also includes a handle 77 for moving the cleaner. The cover 75 has an air outlet 84 for discharging the slip stream from the fan 73 out of the body 72.
The nozzle 71 has a suction port 78 formed in its bottom for sucking dust. The suction port 78 and the dust bag 74 are connected by a suction passage 79. The nozzle 71 also has a blow outlet 80 formed in its bottom and in front of the suction port 78. The blow outlet 80 and the body 72 are connected by a reflux passage 81.
The operation of the electric fan 73 produces a suction flow 82 and a slip stream at the same time. Part 83 of the slip stream is discharged from the cleaner body 72 through the air outlet 84. The other part 85 of the slip stream is directed through the reflux passage 81 and the blow outlet 80 to the surface 90 being cleaned. This blows dust off the surface 90. The blown dust is sucked into the suction port 78 by the suction flow, and flows through the suction passage 79 into the dust bag 74, where it is collected. Air flows from the suction port 78 through the suction passage 79, the bag 74, the reflux passage 81 and the blow outlet 80 in order onto the surface 90, and then returns to the suction port 78. This forms a circulation passage for circulating a flow of sucked air.
FIG. 19 is a sectional side view of another nozzle 86 having a different structure. The nozzle 86 has a blow outlet 87, which is similar to the outlet 80, and a suction port 88 formed in the rear of the outlet 87. The nozzle 86 is fitted with a rotating brush 89 in the suction port 88. The brush 89 can be rotated by the driving force transmitted from an electric motor through a belt. The brush 89 can brush the surface 90 being cleaned. Without the brush 89, the air flow from the outlet 87 might not be able to separate dust from a carpet or the like, to which they are liable to cling or stick. The brush 89 can scratch up or throw up dust to separate them from the surface 90.
According to the above cleaner, because the blow outlet and the suction port are isolated from each other by a wall, air does not flow from the outlet directly to the rotating brush. Therefore, waste threads, hairs, etc. tend to cling to the brush. Moreover, part of the air from the blow outlet is liable to flow out of the nozzle through the gap between the nozzle and the surface. Consequently, the dust blown off the surface being cleaned may spread around the nozzle, and the suction capacity of the cleaner may decrease.